Yarn winding method and apparatus and package formed thereby

ABSTRACT

To reliably carry out the yarn-catching operation and formation of bunch-winding and tail-winding, while using a bobbin having no yarn-catching groove thereon, and obtain a package with a shorter yarn end extended from the bunch-winding part, upstream of a pressure roller 7, a yarn-holding guide 24 is provided for guiding a running yarn to a bunch-winding position; downstream of an empty bobbin 70, a yarn-searching guide 29 is provided for guiding the yarn to the yarn-catching part or a threading guide 33 and a yarn-winding guide 37 movable toward a concave space (A) formed by the pressure roller 7 and the empty bobbin 70 carried on a spindle 4 to guide the yarn 80 running to a full bobbin 70&#39; or others to a yarn-catching part B formed between the abutting end walls of adjacent empty bobbins 70 carried on the spindle 4.

FIELD OF THE INVENTION

The present invention relates to a method for taking up a yarn on abobbin formed of any kind of material, with an appropriate initialWinding, bunch winding and tail winding, a winder used therefor, abobbin used therefor and a yarn package obtained by the method.

DESCRIPTION OF THE RELATED ART

In general, synthetic fiber yarns spun from a spinning machine are takenup by a turret type winder such as disclosed in Japanese UnexaminedPatent Publication (Kokai) No. 62-280172.

The abovesaid turret type winder rotatably carries a plurality, ofspindles, and comprises a turret member rotatably secured on a machineframe, a traverse mechanism provided above the spindle, a contact rollerfor applying a predetermined pressure in a contacting manner to a bobbinfixedly carried on the spindle or a yarn layer section wound on thebobbin, an upper yarn-switching mechanism provided above the traversemechanism or the contact roller, a lower yarn-switching mechanismprovided between a full bobbin and an empty bobbin, for restricting ayarn path when switching the yarn from the full bobbin to the emptybobbin, a threading mechanism provided beneath the lower yarn-switchingmechanism, for restricting a yarn path when the yarn is wound on theempty bobbin, and an initial-winding forming mechanism movable betweenthe empty bobbin and the lower yarn-switching mechanism or between theempty bobbin and the threading mechanism, for forming the initialwinding on the empty bobbin.

When a yarn is taken up by the abovesaid turret type winder, a bobbin 75made of paper is used, having a yarn-catching groove 75A at one endthereof, consisting of a yarn introduction part 75a having a V-shapedcross section and a yarn-catching part 75b having a thinner crosssection, as shown in FIGS. 44 and 45.

In order to prevent the yarn caught by the yarn-catching groove fromescaping, the opposite side walls of the yarn-catching part 75b arebrought into tight contact with each other by collapsing the outerperiphery of the bobbin 75, as shown in FIG. 46.

When initiating the yarn take-up operation while using such a bobbin 75,a plurality of yarns spun from a spinning machine (not shown) are suckedinto a suction gun (not shown), each of which is inserted to a firstyarn path restricting guide of the threading mechanism, after ayarn-removing guide of the upper yarn-switching mechanism has come outto move the first yarn path restricting guide to a position at which theinitial-yarn winding operation is conducted- Then a yarn-pushing guideof the first yarn-switching mechanism moves toward one end of an emptybobbin to convey the respective yarn thereby onto a vertical linepassing a position of the respective bobbin at which a bunch winding isto be formed.

Next, when a yarn-winding guide of the initial-winding forming mechanismmoves to a yarn-running position to bring the yarn which is moving whilebeing guided by the yarn-pushing guide and the first yarn pathrestricting guide of the threading mechanism, into contact with theempty bobbin, the yarn engages with the yarn-catching groove of theempty bobbin and is caught thereby, due to the movement of theyarn-winding guide in the lengthwise direction of the empty bobbin.Then, the yarn-running direction is abruptly reversed, whereby the yarnis broken by a tensile force applied thereto due to the suction of thesuction gun (not shown) and the drag of the empty bobbin and a freshyarn continuously delivered from the contact roller is wound in theyarn-catching groove of the empty bobbin. Since the yarn is guided bythe yarn-pushing guide to run toward a position at which a bunch-windingis to be formed, the yarn is wound at this predetermined position as abunch-winding while moving along the outer periphery of the emptybobbin.

When a yarn is switched from a full bobbin to a fresh empty bobbin aftera predetermined amount of yarn has been taken up on the bobbin 75, theturret member rotates to move the full bobbin from a yarn-windingposition to a doffing position and, on the contrary, to move the emptybobbin from the doffing position to the yarn-winding position.

When the yarn is removed from the traverse guide by the yarn-removingguide of the upper yarn-switching mechanism and conveyed to a bobbin endby the yarn-pushing guide, a second yarn path restricting guide of thelower yarn-switching mechanism moves to a position between the fullbobbin and the empty bobbin to guide the yarn winding on the full bobbinto the bunch-winding position.

Then the yarn-winding guide of the initial-winding forming mechanismmoves between the empty bobbin and the second yarn path restrictingguide of the initial-winding forming mechanism to bring the yarn whichis running while being restricted by the yarn-pushing guide of the upperyarn-switching mechanism and the second yarn path restricting guide ofthe lower yarn-switching mechanism, into contact with outer periphery ofthe empty bobbin. Thereupon, the yarn engages with the yarn-windingguide, moves therewith along the lengthwise direction of the emptybobbin, and is finally caught by the yarn-catching groove. When the yarnis caught, the yarn is abruptly broken because both the full and emptybobbins rotate in the same yarn-winding direction, and thus the yarn isswitched from the full-bobbin to the empty bobbin.

Since the yarn is guided by the yarn-pushing guide to move toward thebunch-winding position of the empty bobbin, the bunch-winding is formedat this predetermined position while the yarn is moved from the yarncatching groove to the outer periphery of the empty bobbin.

Since a yarn path formed by the yarn-pushing guide of the upperyarn-switching mechanism and the first yarn path restricting guide ofthe threading mechanism, or the yarn-pushing guide of the loweryarn-switching mechanism and the second yarn path restricting guidecrosses the introduction part 75a of the yarn-catching groove 75Aprovided on the empty bobbin, the yarn is liable not to enter theyarn-catching part 75b even though the yarn runs while contacting theintroduction part 75a of the yarn-catching groove 75A. Also, even thoughan operation for detecting the yarn-catching groove is conducted bymoving the yarn-winding guide in the lengthwise direction of the emptybobbin 75, the yarn does not assuredly enter the yarn-catching part 75bbecause the yarn does not move in a parallel state relative to theyarn-catching groove 75A in a similar manner to the above, thusdeteriorating the yarn-switching operation.

Further, since a cross-section of the yarn-catching groove 75A of thebobbin 75 consists of a V-shaped section of the introduction part 75aand a tightly-contacting section of the yarn-catching part 75b, the yarnbecomes fluffy due to the single-filament breakage caused by a burrysurface of the collapsed yarn-catching part 75b, and part of such a yarnremains in the yarn-catching part 75b. Accordingly, there is a problemin that not only the bunch-winding yarn but also the fluffy yarnremaining while being caught by burrs of the yarn-catching part 75b mustbe removed.

In addition, when the yarn has once been wound on the bobbin 75, theyarn-catching groove 75A may deform, or even the outer periphery thereofmay deform by the compression due to the tightening of wound yarn.

In such a bobbin 75, the yarn end firmly entering the yarn-catchinggroove 75A cannot completely be removed therefrom, and when such abobbin is reused, the yarn may not be caught by the yarn-catching groove75A making the yarn-switching operation fail. Further, yarn breakage mayoccur due to an abnormal winding speed caused by the deformed outerperiphery of bobbin. Therefore, reuse of the bobbin may be impossible.

Alternatively, a bobbin without a yarn-catching groove may be adoptedwhile using, as the yarn-catching groove during the yarn-switchingoperation, a contacting portion between the adjacent bobbins fixedlycarried on a spindle or between one end surface of a bobbin and a sidewall of a positioning shoulder of the spindle, and forming thebunch-winding at a position apart from the contacting portion. Since ayarn path formed by a yarn-pushing guide of an upper yarn-switchingmechanism and a second yarn path restricting guide of a loweryarn-switching mechanism is not parallel to the contacting portion butintersects at a large angle, there is a problem in that the yarn isdifficult to enter into the contact portion which lowers the rate ofsuccess of the yarn-switching operation.

To solve this problem, the yarn-switching operation may be conductedwhile providing the bunch-winding position closer to the contactingportion so that the intersecting angle of the yarn relative to thecontacting portion is smaller to place the yarn substantially parallelto the latter. According to this method, the yarn can easily enter thecontact portion to improve the rate of success of the yarn-switchingoperation. In this case, however, the bunch-winding may drop off thebobbin during the doffing operation or when the yarn package is handledin the succeeding process, since the bunch-winding is formed in thevicinity of the contacting portion or the side wall of bobbin end. Thusthere is a problem of the disappearance of tail winding.

The above problems are not limited to a turret type winder but similarlyoccur in a yarn winder wherein a single spindle is provided and a fullbobbin is replaced by an empty bobbin while stopping the spindlerotation.

In Japanese Unexamined Patent Publication (Kokai) No. 51-43411, a bobbinof the above-described type having no yarn-catching groove is proposed,wherein a yarn-introduction part having a U-shaped cross section and ayarn-catching part formed by the contacting side walls of bobbin endsare created when two bobbins abut to each other, or a yarn-catching partis created by abutting two bobbins, each having a slanted surfaceprojected in the lengthwise direction from the outer peripheral edge tothe inner peripheral edge thereof, having a V-shaped cross sectionformed of the slanted surfaces.

When the yarn-introduction part has a U-shaped cross section, the yarncaught thereby is not brought into contact with the vertical wall of theU-shaped groove, whereby a frictional force which causes the yarn tomove to the outer periphery of the bobbin is not generated between theyarn and the wall. Accordingly, the Tarn tends to be wound in theU-shaped groove and must be removed therefrom by the operator during thedoffing operation or the conveyance of the yarn package, to prevent thewould yarn from hanging down. This also causes a large amount of wasteyarn.

Further, there is a problem in that a mechanism for moving the yarncaught by the U-shaped groove, to a bunch-winding position must beadditionally provided.

While, if the yarn-catching part has a V-shaped cross section, there isa difference between the outer diameter of the bobbin and the bottomdiameter of the V-shaped groove, generally corresponding to a wallthickness of the bobbin.

Accordingly, when the yarn-switching operation is carried out in theturret type winder wherein a turret member on which a plurality ofspindles fixedly carrying bobbins are rotatably mounted is made torotate to move one spindle carrying the full package from theyarn-winding winding position to the doffing position and the otherspindle carrying the empty bobbin from the doffing position to theyarn-winding position, the peripheral speed of the bottom of theyarn-catching V-shaped groove is lower by a value corresponding to thewall thickness than the peripheral speed of the bobbin, which causes thereduction of yarn tension to result in the failure of yarn-catching bythe V-shaped groove.

Even though the yarn is caught thereby, the yarn is liable to be woundaround a roller provided upstream of the winder due to the reduction ofyarn tension.

As a result, the success rate of the yarn-switching operation from thefull bobbin to the empty bobbin lowers to a value less than 10%.

On the other hand, a bobbin which can be reused is proposed in JapaneseExamined Utility Model Publication No. 2-3477, having a stepped portionat one end for the connection to the adjacent bobbin.

When the yarn-winding operation is carried out while using such bobbins,the bunch-winding is formed on the boundary part between bobbins. If therespective full bobbins are doffed while being separated from eachother, the bunch-winding is liable to come loose and entangle with otherfull packages during the transportation of full bobbins or the treatmentof bunch-winding.

Alternatively, Japanese Examined Patent Publication No. 57-36233discloses a turret type winder wherein the above second yarn pathrestricting guide is not provided but the spindle fixedly carrying thefull bobbin or empty bobbin is displaceable in the lengthwise direction.The yarn-switching operation from the full bobbin to the empty bobbin isconducted so that the yarn runs to a yarn-catching groove of the emptybobbin and a bunch-winding position on a yarn layer section of the fullbobbin by the action of the first yarn path restricting guide of theupper yarn-switching mechanism.

When the yarn-switching operation is conducted by this turret typewinder, the yarn is liable to pass over the boundary part betweenbobbins before being firmly caught thereby if the spindle-movement speedis too high, resulting in the lowering of the success rate of theyarn-switching operation. Contrarily, if the spindle-movement speed istoo low, the yarn is liable to be spirally wound around the bobbin afterbeing caught by the boundary part and before reaching the bunch-windingposition, resulting in a problem that the spirally wound yarn comesloose to hang down from the full bobbin and entangles with other fullbobbins.

The yarn path in the above yarn-switching operation is illustrated inFIG. 47, as seen from one end of the bobbin 75 in the lengthwisedirection, wherein an angle θ' between a position Q' at which the yarn80 is caught by the empty bobbin 75 and a position P at which thecontact roller 7 is brought into contact with the bobbin 75 and thewinding operation is initiated is in a range of 70° and 90°.Accordingly, the winding tension of the yarn 80 reduces until the yarn80 is caught to initiate the winding operation, which causes the yarn 80to be wound around a delivery roller disposed upstream of the winder,resulting in the lowering of the success rate of the yarn-switchingoperation.

To avoid the lowering of yarn tension during the yarn-switchingoperation, the rotational speed of the full bobbin may be set higherthan the usual speed to increase the winding tension upon theyarn-switching.

That is, as shown in FIG. 49, in the method for temporarily increasingthe yarn take-up speed, it is certainly understood that the yarn tensionsharply increases. However, the yarn-switching operation often fails inthis case since the yarn tension suddenly drops when the yarn isswitched.

In FIG. 49, T₁ illustrates a variation of yarn tension whilerepresenting a yarn-winding period on the horizontal axis and a supplyside yarn tension on the vertical axis, when the yarn speed increases by2% at a yarn-switching instant.

As understood from graph T₁, since the rotational speed of bobbinincreases immediately before instant t₁ for initiating theyarn-switching operation, the yarn tension also becomes gradually higherand, when the yarn is brought into contact with a bunch-winding guide atinstant t₂, it reaches the maximum value. Then the yarn tension sharplyfalls at instant t₃ at which the yarn is actually broken, andthereafter, sharply increases if the yarn-switching is successful. Thusthe yarn winding operation is normally continued.

In other words, it is understood that there is a risk of failure of theyarn-switching operation in the conventional method due to the sharpdrop of yarn tension.

A first problem is that a bobbin having a V-shaped yarn-catching groovecannot always catch the yarn during the threading operation and theyarn-switching operation and further be repeatedly used.

A second problem is that in a bobbin forming a V-shaped or U-shapedyarn-catching part on the boundary between the adjacent bobbins, theyarn caught thereby cannot readily move to the outer periphery of thebobbin.

A third problem is that the success rate of the yarn-switching operationbecomes worse due to the sharp fall of yarn tension in a period from theyarn being caught by the yarn-catching part to the initiation ofyarn-winding operation.

A fourth problem is that the handling of full bobbin becomes difficultsince the yarn end of the bunch-winding is not anchored and tends tohang down therefrom during the doffing or transportation of the fullbobbin.

An object of the present invention is to solve the above problems of theprior art and provide a yarn winding method wherein the yarn-catching,bunch-winding and tail-winding are assuredly carried out even by using abobbin made of synthetic resin or aluminum alloy having no yarn-catchinggroove thereon, a winder for carrying out the method, a bobbin usedtherefor and a yarn package obtained by the yarn winding method, whichis free from the yarn hanging down from the bunch-winding and entanglingwith another package during the doffing operation and has an easilyremovable bunch-winding.

DISCLOSURE OF THE INVENTION

To solve the first and second problems of the present invention, a yarnwinding method according to the present invention comprises the steps ofengaging a running yarn with a yarn-catching part formed by a boundarypart between ends of the adjacent bobbins fixedly carried on a spindleor a boundary part between one end of a bobbin and a side wall of astepped portion of the spindle for positioning the bobbin, moving theyarn from the yarn-catching part to a bunch-winding position of therespective bobbin immediately after the yarn is caught by theyarn-catching part, forming a bunch-winding at the bunch-windingposition, forming a predetermined tail-winding, and initiating thenormal yarn winding operation while reciprocating the yarn by a traverseguide.

To solve the third problem, a winder according to the present inventioncomprises an upper yarn path restricting guide upstream of a contactroller, for guiding a running yarn to a bunch-winding position, and ayarn-winding guide for engaging the yarn running while being guided bythe upper yarn path restricting guide with a yarn-catching part of anempty bobbin fixedly carried on a spindle, positioned in a concave spaceformed between the contact roller and the empty bobbin fixedly carriedon the spindle.

To solve the first, second and third problems, a winder according to thepresent invention comprises an upper yarn path restricting guideupstream of a contact roller, for guiding a running yarn to abunch-winding position, and a yarn-winding guide for engaging the yarnrunning while being guided by the upper yarn path restricting guide witha yarn-catching part of an empty bobbin fixedly carried on a spindle,positioned in a concave space formed between the contact roller and theempty bobbin; the yarn-catching part being formed by a boundary partbetween ends of the adjacent bobbins fixedly carried on a spindle or aboundary part between one end of a bobbin and a side wall of a steppedportion of the spindle for positioning the bobbin.

To solve the first and second problems, a yarn-winding bobbin accordingto the preset invention may have at least one end surface of acylindrical hollow body, formed by an inner side wall generallyperpendicular to a lengthwise axis of the cylindrical body and an outerslanted wall extending outward from the outer edge of the cylindricalbody to the side wall and connected with the outer periphery of thecylindrical body via a circular cross-sectional wall having a radius ofcurvature of not more than 2 mm. Alternatively, the bobbin may have astructure wherein each of the opposite ends of a cylindrical body isformed by a side wall generally perpendicular to a lengthwise axis ofthe cylindrical body and wherein one of the side walls is connected withthe outer edge of the cylindrical body via a circular cross-sectionalwall having a radius of curvature of not more than 2 mm and the other ofthe side walls is connected with the outer edge of the cylindrical bodyvia a circular cross-sectional wall having a radius of curvature largerthan that of the former circular cross-sectional wall. Further, thebobbin may alternatively be formed of a cylindrical body of laminatedpaper wherein a side wall of the respective end or one end of thecylindrical body and the outer periphery of the cylindrical body in thevicinity thereof are covered with a protective member.

To solve the fourth problem, a yarn package according to the presentinvention is formed on a bobbin having at least one end surface of acylindrical hollow body, formed by an inner side wall generallyperpendicular to a lengthwise axis of the cylindrical body and an outerslanted wall extending outward from the side wall and connected with theouter periphery of the cylindrical body via a circular cross-sectionalwall having a radius of curvature of not more than 2 mm, whilesequentially forming from the end of the cylindrical body abunch-winding for anchoring a yarn end, a tail-winding and substantialyarn-layers. The yarn package may be formed on a bobbin having astructure wherein each of the opposite ends of a cylindrical body isformed by a side wall generally perpendicular to a lengthwise axis ofthe cylindrical body and wherein one of the side walls is connected withthe outer edge of the cylindrical body via a circular cross-sectionalwall having a radius of curvature of not more than 2 mm and the other ofthe side walls is connected with the outer edge of the cylindrical bodyvia a circular cross-sectional wall having a radius of curvature largerthan that of the former circular cross-sectional wall, whilesequentially forming from the end of the cylindrical body abunch-winding for anchoring a yarn end, a tail-winding and substantialyarn-layers. Alternatively, the yarn package may be formed on a bobbinformed of a cylindrical body of laminated paper wherein a side wall ofthe respective end or one end of the cylindrical body and the outerperiphery of the cylindrical body in the vicinity thereof are coveredwith a protective member, while sequentially forming from the end of thecylindrical body a bunch-winding for anchoring a yarn end, atail-winding and substantial yarn-layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of a first embodiment of a yarn winderaccording to the present invention;

FIG. 2 is a cross section taken along a line 2--2 of FIG. 1;

FIG. 3 is a cross section illustrating a detailed structure of a spindleof FIG. 1;

FIG. 4 is an enlarged view of area IV of FIG. 1;

FIG. 5 is a view seen in the arrowed direction V of FIG. 4;

FIG. 6 is an enlarged view of a lower yarn-switching mechanism of FIG.1;

FIG. 7 is a cross section taken along a line 7--7 of FIG. 6;

FIG. 8 is a schematic view of a second embodiment of a spindle in theyarn winder according to the present invention;

FIG. 9 is a schematic view of a third embodiment of a spindle in theyarn winder according to the present invention;

FIG. 10 is a schematic view of a fourth embodiment of a spindle in theyarn winder according to the present invention;

FIG. 11 is a schematic view of a first embodiment of a bobbin used inthe yarn winder according to the present invention;

FIG. 12 is a schematic view of a second embodiment of a bobbin used inthe yarn winder according to the present invention;

FIGS. 13 through 18 are fragmentary perspective views illustrating thesequential steps, respectively, at an initial stage of the yarn windingoperation of the first yarn winder according to the present invention;

FIG. 19 illustrates a yarn path in the first yarn winder when a yarn isinitially wound on a bobbin;

FIG. 20 is an enlarged view of a boundary part between bobbins forcatching a yarn;

FIGS. 21 through 26 are fragmentary perspective views illustrating thesequential steps, respectively, of the yarn-switching operation of thefirst yarn winder;

FIG. 27 is a front view of a second embodiment of a yarn winderaccording to the present invention;

FIG. 28 is a cross section taken along a line 28--28 of FIG. 27;

FIGS. 29 through 31 are fragmentary front elevation views illustratingyarn-switching operation of the second yarn winder according to thepresent invention;

FIG. 32 illustrates a first yarn-switching operation of the second yarnwinder according to the present invention;

FIG. 33 is a schematic perspective view of a bobbin according to thepresent invention mounted on a spindle;

FIG. 34 is a schematic perspective view illustrating a shape of a secondembodiment of a bobbin;

FIG. 35 is an enlarged view of area XXXV Of FIG. 33;

FIG. 36 is an enlarged view of a shape of bobbin end other than FIG. 35;

FIG. 37 is a schematic enlarged view of area XXXVII of FIG. 34,illustrating a shape of a second embodiment of a bobbin according to thepresent invention;

FIG. 38 is a schematic cross section illustrating a shape of a thirdembodiment of a bobbin according to the present invention;

FIG. 39 is a schematic cross section illustrating a shape of a fourthembodiment of a bobbin according to the present invention;

FIG. 40 is a schematic illustration of a shape of a first embodiment ofa yarn package according to the present invention;

FIG. 41 is a schematic illustration of a shape of a second embodiment ofa yarn package according to the present invention;

FIG. 42 is a schematic illustration of a shape of a third embodiment ofa yarn package according to the present invention;

FIG. 43 is a schematic illustration of a device for testing a stabilityof yarn caught on a bobbin;

FIG. 44 is a schematic illustration of one embodiment of a bobbin usedfor the conventional yarn winder;

FIG. 45 is a cross section taken along a line 45--45 of FIG. 44;

FIG. 46 is a cross section taken along a line 46--46 of FIG. 44;

FIG. 47 is a schematic illustration of a yarn path in the initial-yarnwinding operation in the conventional winder;

FIG. 48 is a graph illustrating the variation of yarn tension during theyarn-switching operation according to the present invention; and

FIG. 49 is a graph illustrating the variation of yarn tension during theconventional yarn-switching operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A yarn-winding method and a yarn package obtained thereby will bedescribed in detail below with reference to the drawings.

Since the yarn-winding method according to the present invention has theabove technical composition, when a yarn engages with a yarn-catchingpart formed in a boundary area between end surfaces of bobbins abuttingto each other or in a boundary area between a side wall of a positioningshoulder and an end surface of a bobbin abutting each other, the yarnimmediately moves from the yarn-catching part to the respectivebunch-winding position to form a bunch-winding on the bobbin.

FIG. 1 is a schematic front view of one embodiment of a turret type yarnwinder according to the present invention, and FIG. 2 is a schematicside view thereof, wherein the yarn winder is structured by a turretmember 2 carried on a machine frame 1 in a rotatable manner, spindles 3,4 carried on the turret member 2 in a rotatable manner for fixedlymounting bobbins, a traverse mechanism 6 carried on a frame 5 movable inthe vertical direction above the spindles 3, 4, a contact roller 7carried on the frame 5 in a rotatable manner, an upper yarn-switchingmechanism 8 provided above the traverse mechanism 6, a loweryarn-switching mechanism 9 carried on the machine frame 1 to be movablebetween a full bobbin 71 and an empty bobbin 70 (FIG. 21), threadingmechanism 10 carried on the machine frame 1 beneath the loweryarn-switching mechanism 9, for restricting a yarn path to wind the yarnonto the empty bobbin at the initial stage of the yarn windingoperation, and an initial yarn-winding forming mechanism 11 carried onthe frame 5 to be movable to a concave space A, as shown in FIG. 4,formed by the contact roller 7 and the empty bobbin 70 located at ayarn-winding position.

The turret member 2 is mounted on the machine frame 1 in a rotatablemanner via a bearing 12 and is driven to rotate by 180° in the direction(a) by a drive means (not shown) when the bobbin fixedly carried on thespindle 3 located at the yarn-winding position becomes full, to bringthe full bobbin to the doffing position, while bringing the spindle 4fixedly carrying the empty bobbin located at the doffing position to theyarn-winding position.

The structure of the spindle 3 or 4 is illustrated in FIG. 3, includinga shaft 13 rotatably supported on the turret member 2 by a bearing 14, apiston 15 movably mounted in a pressurized air chamber 13b formed in adistal end portion of the shaft 13, a spring 16 for pushing the piston15 to the support side, fixing rings 17 fitted onto the outer peripheryof the shaft 13, and tubular bodies 18, 19, wherein an output shaft of amotor (not shown) is coupled to a base end of the shaft 13.

A central hole 13a for supplying pressurized air is provided in theshaft 13 along the axis thereof, to which a pressurized air supplyingpipe (not shown) with a solenoid valve is connected. In the end portionon the support side, the shaft 13 has shoulders 13c and 13d on theperiphery thereof for abutting to the bobbin and the fixing ring,respectively. It may be possible to provide a ring 39 fitted onto theend portion of the shaft 13, having a groove 39a, into which a pushingpiece 42 for pushing the bobbin is engaged as shown in FIG. 8, insteadof providing the shoulder 13d for abutting to the fixing ring.

When the pressurized air is supplied to the hole 13a of the shaft 13, apushing force acting on the piston 15 is moved the same in the direction(b) to eliminate the pressure on the respective fixing ring 17, wherebythe respective fixing ring 17 restores to its original size having anouter diameter smaller than an inner diameter of the empty bobbin 70. Ifthe bobbin 70 is fitted onto the outer peripheries of the fixing rings17 and the tubular bodies 18, 19 while maintaining this state and thenthe supply of the pressurized air to the hole 13a of the shaft 13 isinterrupted, the piston 15 is moved in the direction (c) by the spring16 to sequentially push the tubular body 18, the fixing ring 17, thetubular body 19 and the fixing ring 17, whereby the fixing rings 17 arewidthwisely compressed to increase the outer diameter thereof andpressingly fix the inner periphery of the bobbin 70.

Details of the upper yarn-switching mechanism 8 are illustrated in FIGS.4 and 5, including a yarn-removing guide 20 pivoted to the frame 5 abovethe traverse mechanism 6 to be displaceable in the yarn runningdirection and the direction perpendicular to the traversing direction, ayarn-pushing guide 22 provided on the frame 5 opposite to theyarn-removing guide 20 while intervening the running yarn therebetweenand displaceable in the lengthwise direction of the empty bobbin 70 by apower cylinder 23, and a yarn-holding guide 24 mounted on the frame 5 tobe located beneath the yarn-pushing guide 22 when the yarn-pushing guide22 moves to a bunch-winding position and a tail-winding position of theempty bobbin 70 so that the yarn is held thereby. The yarn-holding guide24 is of an L-shape having a yarn-holding section 24a and a guidingsection 24b for guiding the yarn to the bunch-winding position.

When the bobbin located in the yarn-winding position becomes full, theyarn-removing guide 20 is made to project by the power cylinder 21 topush out the yarn from a traverse guide 6a of the traverse mechanism 6.Then the yarn-pushing guide 22 moves to an end (c) of the full bobbin70' by the power cylinder 23, whereby the yarn removed from the traverseguide 6a is transported to the end of the empty bobbin 70 and guided bythe yarn-holding guide 24 to a yarn-catching part B.

The lower yarn-switching mechanism 9 has a structure shown in FIGS. 6and 7, including an arm 25 pivoted to the machine frame 1, a sectionplate 26 pivoted to one end of the arm 25, a power cylinder 27 forpivoting the arm 25, a power cylinder 28 for rotating the section plate26, a yarn-searching guide 29 provided on the upper side of the distalend of the section plate 26 to be movable in the lengthwise direction ofthe bobbin so that it is positioned on the empty bobbin side when thesection plate 26 moves to the yarn-switching position, and abunch-winding forming guide 30 provided on the lower side of the distalend of the section plate 26 to be positioned on the full bobbin side ofthe section plate 26 at the above state, wherein the yarn-searchingguide 29 is movable in the lengthwise direction of the empty bobbin 70by a power cylinder 31.

During the yarn-switching operation, the arm 25 first is moved by thepower cylinder 27 to a position between the empty bobbin 70 located atthe yarn-winding position and the full bobbin 70' located at the doffingposition and then the section plate 26 follows this by the action of thepower cylinder 28, so that the yarn 80 is guided by the bunch-windingforming guide 30 to a bunch-winding position in the yarn-layer sectionof the full bobbin 70'. Then the yarn-searching guide 29 moves in thelengthwise direction of the empty bobbin 70 to guide the yarn to runalong a vertical line passing over the yarn-catching part B.

The threading mechanism 10 has a structure including a holding lever 32pivoted to the machine frame 1 at a position beneath the loweryarn-switching mechanism 9 and movable in the lengthwise direction ofthe spindle, an arm 34 mounted to the lever 32 and having a threadingguide 33 at one end thereof, and a power cylinder (not shown) forrotating the holding lever 32 to move the threading guide 33 between athreading position and a Waiting position.

When the yarn 80 is threaded to the threading guide 33 at the initialstage of the yarn-winding operation, the threading guide 33 is made tomove together with the holding lever 32 by the power cylinder (notshown) toward the threading position so that yarn 80 is guided to passover the yarn-catching part B.

As shown in FIG. 4, the initial-yarn winding mechanism 11 includes anarm 36 pivoted to the frame 5, a yarn-winding guide 37 carried at oneend of the arm 36 to be located beneath the traverse mechanism 6, and apower cylinder 38 for rotating the arm 36. In FIGS. 13 and 14, theyarn-winding guide 37 has a guiding portion 37a such as a shoulder or arecess (not shown) preferably formed by ceramics or alumina for guidingthe yarn to the yarn-catching part B.

While the yarn 80 runs along a yarn path restricted by the yarn-pushingguide 22, the yarn-holding guide 24 and the bunch-winding forming guide30, the arm 36 is made to rotate by the power cylinder 38 to project theyarn-winding guide 37 into a concave space A between the contact roller7 and the empty bobbin 70 located at the yarn-winding position so thatthe yarn 80 is guided to engage with the yarn-catching part B.

Each of the above power cylinders is connected to a pressurized airsupply pipe (not shown) having a solenoid valve for switching apressurized air supply path by a signal from a controller to extend andretreat the piston thereof.

The threading operation at the initial stage of the yarn windingoperation will be described next with reference to FIGS. 13 through 18.

In the initial stage of the yarn winding operation in the turret typeyarn winder, the yarn 80 spun from a spinning machine (not shown) issucked by a suction gun 100 as shown in FIG. 13. When the yarn-removingguide 20 is projected, inserted into the threading guide 33 of thethreading mechanism 10, the threading guide 33 moves in the arroweddirection (c) to the initial-yarn winding position, as shown in FIG. 14.

Then, the yarn-pushing guide 22 of the upper yarn-switching mechanism 8moves to the end (c) of the empty bobbin 70 so that the yarn 80 isconveyed generally onto the vertical line passing over the bunch-windingposition provided at the end of the empty bobbin 70.

Then, as shown in FIG. 15, the yarn-winding guide 37 of theinitial-yarn-winding mechanism 11 is projected into the concave space Aformed between the contact roller 7 and the empty bobbin 70 so that theyarn 80 is guided to pass over the yarn-catching part B formed by aboundary part between the ends of the adjacent empty bobbins 70 abuttingeach other and a boundary part between the end of the empty bobbin 70and the end 13c of the shaft 13 abutting each other. If the yarn 80 runsdirectly over the yarn-catching part B, it instantly cuts into theyarn-catching part B and is caught thereby While, if the yarn 80 runsdeviated from the yarn-catching part B, the yarn-catching guide 33 ismoved in the direction (b) so that the yarn 80 cuts into theyarn-catching part B.

when the yarn 80 is caught by the yarn-catching part B by the aboveoperation, an angle θ between a point Q at which the yarn 80 is caughtby the empty bobbin 70 and a point P at which the contact roller 7 comesinto contact with the empty bobbin 70 becomes smaller to a value in arange of 30° through 50° Accordingly, a period before the empty bobbin70 starts the rotation to initiate the take-up operation of the yarn 80is cut by half compared to the conventional case, for which period thewinding tension is lowered.

Since both of the empty bobbin 70 and full bobbin 70' rotate in the samedirection, i.e., the yarn winding direction, the yarn 80 is tensed andbroken between both the bobbins 70 and 70'. Then as shown in FIG. 16,the yarn 80 caught by the yarn-catching part B is released from a recess37a of the yarn winding guide 37 soon after the bobbin 70 rotates by apredetermined amount (30° through 50°) and tends to move toward abunch-winding forming yarn path restricted by the guiding section 24b ofthe yarn-holding guide 24.

If the yarn catching part B is formed as shown in FIG. 20 to have anarcuate portion R-1 with a smaller radius of curvature on one side overwhich the yarn is transferred to the bunch-winding position and anarcuate portion R-2 with a larger radius of curvature on the oppositeside, the width of the opening of the yarn-catching part B becomeslarge, whereby the yarn 80 easily cuts into the yarn-catching part B andis assuredly caught thereby. Also the yarn 80 released from the guidingshoulder of the yarn-winding guide 37 assuredly comes into contact withthe arcuate portion R-1 with a smaller radius of curvature formed at theend of the empty bobbin 70, whereby the yarn 80 can easily ride on theouter periphery of the empty bobbin 70 and is moved to the bunch-windingforming position. Accordingly, a yarn length from the yarn-catchingposition in the yarn-catching part B to the bunch-winding startingposition becomes short.

When the predetermined amount of bunch-winding C is formed, as shown inFIG. 17, the yarn-pushing guide 22 returns to the waiting position at apreset speed to form a tail-winding D. During this step, the yarn 80slidingly moves on the holding section 24b of the yarn-holding guide 24and is released from the yarn-holding guide 24 after the formation oftail-winding D.

Then the yarn 80 laterally moves to a fulcrum side of the traversemotion and is caught by the traverse guide 6a of the traverse mechanism6 as shown in FIG. 18 to be subjected to a traverse motion, whereby theyarn 80 is wound on the empty bobbin 70.

Next, the yarn-switching operation from the full bobbin to the emptybobbin will be described with reference to FIGS. 21 through 26.

When a bobbin becomes full after a predetermined amount of yarn 80 hasbeen wound thereon the turret member 2 is made to rotate to move thefull bobbin 70' located at a yarn-winding position to a doffing positionand, instead, to move an empty bobbin 70 located at the doffing positionto the yarn-winding position.

Then as shown in FIG. 21, the arm 25 and the section plate 26 of thelower yarn-switching mechanism 9 is made to rotate to a position betweenthe empty bobbin 70 and the full bobbin 70'. Simultaneously with thisoperation, the yarn-removing guide 20 of the upper yarn-switchingmechanism 8 is moved perpendicular to the yarn running direction torelease the yarn 80 from the traverse guide 6a of the traverse mechanism6, whereby the yarn 80 laterally moves to a fulcrum side of the traversemotion.

Then, as shown in FIG. 22, the yarn-pushing guide 22 catches the yarn 80in the midway of movement in the direction (c) from the waiting positionto convey the same to the bunch-winding forming position. Simultaneouslywith this operation, the yarn-searching guide 29 is moved in thedirection (c)

The yarn-searching guide 29 moves to a position at which the yarn 80 canrun on the vertical line common to that of the yarn-winding guide 37 ofthe initial-winding forming mechanism 11. At that time, the yarn runstoward the full bobbin 70' while being restricted by the bunch-windingforming guide 30, and forms a bunch-winding E on the yarn later section90a.

As shown in FIG. 23, the yarn-winding guide 37 of the initial-windingforming mechanism 11 projects into the concave space A formed by thecontact roller 7 and the empty bobbin 70 located at the yarn windingposition, whereby the yarn 80 is guided to engage with the yarn-catchingpart B formed by the boundary part between the ends of the adjacentempty bobbins 70 abutting each other and the boundary part between oneend of the empty bobbin 70 and one end 12c of the shaft 12 abutting eachother. At this time, if the yarn 80 runs at the same position as theyarn-catching part B, the yarn 80 instantly cuts into the yarn-catchingpart B and is caught thereby. While, if the yarn 80 runs deviated fromthe yarn-catching part B, the yarn 80 cuts into the yarn-catching part Band is caught thereby midway in the movement of the yarn-searching guide29 in the direction (c).

When the yarn 80 cuts into the yarn-catching part B and is caughtthereby according the above operation, the yarn 80 is tensed and brokenbetween the empty bobbin 70 and the full bobbin 70' because both theempty bobbin and full bobbin rotate in the same yarn-winding directionas shown in FIG. 19. The yarn 80 caught by the boundary part B as shownin FIG. 24 is soon released from the yarn winding guide 37 when thebobbin 70 rotates by a predetermined amount (30° through 50°), andconveyed to the bunch-winding forming position under the restriction ofthe guiding section 24b of the yarn-holding guide 24.

When a predetermined amount of bunch-winding C is formed, as shown inFIG. 25, the yarn-pushing guide 22 returns the waiting position at apredetermined speed to form the tail-winding. At that time, the yarn 80slidingly moves on the holding section 24a of the yarn-holding guide 24and releases from the yarn-holding guide 24 after the tail-winding hasbeen formed.

Then the yarn moves laterally to the fulcrum side of the traverse motionand is caught by the traverse guide 6a of the traverse mechanism 6 asshown in FIG. 26 to be subjected to the traverse motion so that the yarn80 is wound on the empty bobbin 70.

Next, the structure of a second embodiment of the turret type yarnwinder according to the present invention will be described withreference to FIGS. 27 and 28.

The winder of the second embodiment includes a turret member 2 pivotedon a machine frame 1, spindles 42 and 43 mounted on the turret member 1,for fixedly carrying bobbins thereon, a traverse mechanism 6 carried ona frame 5 movable up and down in the vertical direction above thespindles 42, 43, a contact roller 7 rotatably mounted on the frame 5, anupper yarn-switching mechanism 8 provided on the frame 5 above thetraverse mechanism 6, a threading mechanism 10 mounted on the machineframe i for restricting a yarn path so that a yarn is wound on an emptybobbin at the initial stage of the yarn winding operation, and aninitial-winding forming mechanism 11 mounted on the frame 5 so that itcan project into a concave space A formed by the contact roller 7 andthe empty bobbin 70 located at the yarn winding position.

The above winder is exactly the same as that shown in FIGS. 1, 3, 4 and5, and therefore the explanation thereof is omitted, except for thestructure for mounting the spindles 42, 43 to the turret member 2.

The spindle 42 or 43 includes a support tube 45 mounted on the turretmember 2 by a slide bearing 44 to be movable in the lengthwise directionthereof, a shaft 47 rotatably mounted on the support tube 45 by abearing 46 in a cantilever manner, a motor 48 coaxially mounted on thesupport tube 45, a coupling 49 for connecting the shaft 47 to an outputshaft of the motor 48, a power cylinder 50 mounted on the turret member2 in parallel to the support tube 45 and having a piston rod 50a coupledto the motor 48, and an anti-rotation pin 51 projected from the turretmember 2 and inserted into the support tube 45.

The shaft 47 has a hole along its axis for supplying pressurized air,and a piston 15 and a spring are provided in the end portion as shown inFIG. 3. According to this structure, tubular bodies 18, 19 fitted on theouter periphery of the shaft 47 move to compress fixing rings 17 fromboth sides and expand the same in the radial direction. Thus the fixingrings 17 pressingly engage with the inner periphery of the bobbin andfix the same.

The power cylinder 50 is connected with a pressurized air supply pipe(not shown) having a solenoid valve which is actuated by a signal from acontroller to switch a pressurized air path so that the piston rod 50aof the power cylinder 50 extends or retreats.

If the piston rod 50a extends by the supply of pressurized air to thepower cylinder 50, the shaft 47 moves together with the support tube 45relative to the turret member 2 to move the spindle 42 in the direction(c) toward the support end, while if the piston rod 50a retreats, thespindle 42 moves in the direction (b) toward the free end.

The yarn-switching operation in the above second winder will bedescribed with reference to FIGS. 29 through 31.

When a predetermined amount of yarn 80 is wound on a bobbin to form afull bobbin, the turret member 2 rotates to move a full bobbin 70'located at the winding position to a doffing position and an emptybobbin 70 located at the doffing position to the winding position.

Then the yarn-removing guide 20 of the upper yarn-switching mechanism 8moves in the direction perpendicular to the yarn running direction topush out the yarn 80 from the traverse guide 6a of the traversemechanism 6, whereby the yarn 80 moves laterally toward the fulcrum oftraverse motion.

Next, the yarn-pushing guide 22 moves from the waiting position in thedirection (c) and catches the yarn 80 in the midway of this movement.When the pushing guide stops at a position F on the common vertical lineso that the yarn 80 runs toward the yarn-catching part B, the powercylinder 50 of the spindle 43 carrying the full bobbin 70' is actuatedto extend the piston rod 50a whereby the spindle 43 moves in thedirection (c) toward the support end as shown in FIG. 29.

The yarn 80 runs while guided by the yarn-pushing guide 22 and is woundon the bunch-winding position E on the yarn layer section 90a of thefull bobbin 70'.

Then the yarn-winding guide 37 of the initial-winding forming mechanism11 projects into the concave space A formed by the contact roller 7 andthe empty bobbin 70 located at the winding position. When engaging withthe yarn 80 running to the bunch-winding position E on the yarn layersection 90a of the full bobbin 70', the yarn-pushing guide 22 moves to aposition G on the common vertical line passing over the bunch-windingforming position C.

When the yarn-winding guide 37 projects to a predetermined position, theyarn 80 cuts into the yarn-catching part B and is caught thereby.

At that time, the power cylinder 50 of the spindle 42 is actuated toretreat the piston rod 50a whereby the empty bobbin 70 moves togetherwith the spindle 42 in the direction (c) to the free end of the spindle42 to carry out the yarn-searching operation. Thus the yarn 80 canassuredly cut into the yarn-catching part B.

When the above yarn-searching operation is carried out, theyarn-catching part B must be first located nearer to the support end ofthe spindle 42 than the position F of the yarn-catching guide 22, and atthe completion of the yarn-searching operation, nearer to the free endof the spindle 42 than the position F of the yarn-catching guide 22.

When the yarn 80 is caught by the yarn-catching part B, as shown in FIG.31, the yarn is released from the yarn-winding guide 37 and wound on thebobbin 70 at the bunch-winding position C.

In this case, if the above yarn-searching operation is carried out whilemoving the spindle 42, the position F of the yarn 80 is restricted bythe yarn-pushing guide 22 so that the yarn runs along the vertical line,since the lateral movement speed of the yarn 80 is faster than that ofthe spindle 42, whereby the yarn 80 slightly moves toward theyarn-catching part B while being wound on the bobbin 70, resulting inthe wrapping wind for preventing the initially wound layer of yarn 80from loosening.

Another yarn-switching operation conducted on the winder of the secondembodiment will be described with reference to FIG. 32.

The yarn-switching from the full bobbin 70' to the empty bobbin 70 canbe conducted in the second winder by moving the spindle 42 carrying theempty bobbin 70 in the direction (b) toward the free end thereof insteadof moving the full bobbin 70', followed by the same steps as above.

In the above embodiment, the yarn-switching operation is conducted whileforming the yarn-catching part B on the support end side of the spindle3, 4. However, the yarn-switching may be conducted while forming theyarn-catching part B on the free end side of the spindle 3, 4 if thestructure shown in FIGS. 9 and 10 is adopted.

In the case of FIG. 9, a detachable ring 40 is fixedly fitted to a freeend of the empty bobbin 70 so that the yarn-catching part B is formed bya boundary part between the end wall of the ring 40 and that of theempty bobbin 70.

While, in the case of FIG. 10, a resiliently deformable stop 41 ismounted to a piston 14 disposed at the free end of the spindle 3, 4 and,when the piston 14 moves to the support end side of the shaft 12 by thespring 15, the stop 41 projects from holes 14a formed on the outerperiphery of the piston 14 and comes into contact with the end wall ofthe empty bobbin 70 to provide the yarn-catching part B.

If notches 70a as shown in FIG. 11 or cuts 70b as shown in FIG. 12 areformed on an end wall of the empty bobbin 70 on the side where the yarnmoves to the bunch-winding forming part, it is possible to moreassuredly catch the yarn and smoothly slide the yarn upward from theyarn-catching part B to the outer periphery of empty bobbin 70 since theyarn is brought into contact with the notch 70a or the like formed onthe end wall of the empty bobbin 70.

Next, another embodiment of yarn-winding bobbin 70 according to thepresent invention will be described below.

FIG. 33 is a schematic perspective view illustrating a spindle carryingyarn-winding bobbins thereon; FIG. 34 is a diagrammatic sectional viewof a second embodiment of a yarn-winding bobbin of FIG. 33; FIG. 35 isan enlarged view of area VI of FIG. 33; and FIG. 36 is an enlarged viewof an end portion of further embodiment of bobbin. The bobbin 70 ismanufactured by laminated paper while the outer periphery thereof iscovered with a surface paper 72. A surface 71a generally parallel to aplane perpendicular to the lengthwise direction of a cylindrical body 71is formed. One or both of end surfaces of the cylindrical body has aplane vertical to the lengthwise direction in a radially inner areathereof and a surface 71b slanted from the edge of the surface 71a tothe outer periphery of the bobbin in the lengthwise direction. Theslanted surface 71b is connected with the outer periphery of thecylindrical body via a rounded edge 71c.

To obtain a suitable dimensions of bobbin 70, bobbin samples wereprepared while varying a thickness t2 of the slanted surface 71b and anangle θ2 between the slanted surface 71b and a line vertical to thelengthwise direction based on a standard cylindrical body prepared by alaminated paper, having an outer diameter D of 126 mm, an inner diameterd of 110 mm, and a wall thickness t1 of 8 mm. The yarn-switching testswere conducted while taking up a polyester yarn of 75 denier on thesesamples in the turret type winder shown in FIGS. 1 and 2 at a runningspeed of 4500 m/min. The results were listed in Tables 1 and 2.

The same results were obtained when a turret type winder of another typeis used instead of the above one, in which bobbins are pushed from afree end to a base end of a spindle so that the respective bobbins areretained on the spindle by a pressing force.

                  TABLE 1                                                         ______________________________________                                                Outer diameter D of bobbin: 126 mm                                            Inner diameter d of bobbin: 110 mm                                            Radius of rounded edge: 1 mm                                               t1      t2      t2/D × 100                                                                       Success                                         θ2                                                                           (mm)    (mm)    (%)      (%)    Cause of failure                         ______________________________________                                        3    8       2       1.6      100                                             3    8       4       3.2      100                                             3    8       5       4        90     Tension reduction                        3    8       8       6.3      10     Tension reduction                        5    8       3       2.3      100                                             8    8       3       2.3      95     Inferior yarn grip                       1    8       3       2.3      90     Inferior yarn grip                       0    8       3       2.3      85     Inferior yarn grip                       ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                                Outer diameter D of bobbin: 126 mm                                            Inner diameter d of bobbin: 110 mm                                    Edge 2c      t2      t2/D × 100                                                                       Success                                                                              Yarn end length                          (mm)   θ2                                                                            (mm)    (%)      (%)    (cm)                                     ______________________________________                                        1      3     3       2.3      100    70                                       2      3     3       2.3      100    115                                      3      3     4       3.2      95     300                                      ______________________________________                                    

It is ideal to form the plane 71a on the bobbin 70 so that an angle (θ1)made between the plane 71a and a vertical line perpendicular to thelongitudinal axis as shown in FIG. 36 becomes 0°. However, since thereis a manufacturing tolerance and the bobbin may be deformed due to thelengthwise compression when the bobbin is fastened on the spindle, theangle (θ1) is preferably in a range within ±2°.

When the outer diameter of bobbin is 126 mm as shown in Table 1, thedistance t2 of the slanted surface 71b from the outer periphery of thebobbin to the surface 71a is preferably not more than 4% of the outerdiameter of bobbin, because, if t2 is less than 3 mm, the peripheralspeed difference becomes larger to extremely lower the yarn tension,which then worsens the success rate of the yarn-switching operation to agreat extent.

Also, as shown in FIG. 35, it is ideal to form the slanted surface 71bso that an angle θ2 relative to a vertical line perpendicular to alongitudinal axis becomes, smaller. However, if the angle θ2 is not morethan 1° as shown in Table 1, the success rate of yarn-switchingoperation is lowered to less than 90% due to inferior yarn-introduction,while, if the angle θ2 reaches 8°, the success rate is also lowered toless than 95% due to insufficient yarn-catching.

Accordingly, the angle θ2 is preferably in a range between 2° and 5° sothat the yarn can be assuredly introduced into the yarn-catching part,and thereafter, brought into contact with the slanted surface 2b andmoved quickly on the outer periphery.

If the edge 71c connecting the slanted surface 71b with the outerperiphery of cylindrical body has a radius of curvature of 3 mm as shownin Table 2, a yarn-end length wound on other than bunch-winding partamounts to 300 cm because the movement from the yarn-catching part tothe outer periphery is delayed. Also the success rate of theyarn-switching operation is lowered to 95% due to the failure ofyarn-catching operation.

Accordingly, the edge 71c is preferably formed to have a radius ofcurvature of less than 2 mm.

The radius of curvature is preferably more than 0.3 mm to prevent damageof the yarn or the generation of fluff which may occur when the yarn isbrought into contact with the edge 71c.

Since the yarn-catching force of the bobbin 70 largely relies on asurface roughness, a test was conducted to determined the favorablesurface roughness of the slanted surface 71b as follows. Slantedsurfaces 71b having the surface roughness of JIS R_(max) 12S and JISR_(max) were prepared. As shown in FIG. 43, a 75d polyester filamentyarn was engaged with the respective slanted surface at a wrapping angleof 30° while tensioned at 30g by means of a portable balance 20. As aresult, the yarn slips when the surface roughness is JIS R_(max) 8S butis broken when the surface roughness is JIS R_(max) 12S.

Thus, the surface roughness of the slanted surface 71b is preferablymore than JIS R_(max) 12S for the purpose of assuredly catching theyarn.

FIG. 37 is an enlarged view of area XXXXVII FIG. 33, for illustrating ashape of a second embodiment of bobbin according to the presentinvention. In this bobbin 70, a cylindrical body 71 is formed bylaminated paper and a surface paper 72. The opposite end surfaces of thecylindrical body 71 are formed by planes 71a1 and 71a2 generallyparallel to a plane perpendicular to the longitudinal axis, and edges71c1 and 71c2 connected the respective planes 71a1, 72a2 with the outerperiphery of the cylindrical body are formed to be arcuate.

Regarding this bobbin, various combinations of dimensions in therespective edges 71c1, 71c2 were prepared similar to the firstembodiment. A yarn-switching test was conducted on these bobbins whilewinding a 75d polyester yarn thereon by a turret type winder at a yarnspeed of 4500 m/min. Results were obtained as listed in Table 3.

                  TABLE 3                                                         ______________________________________                                                Outer diameter D of bobbin: 126 mm                                            Inner diameter d of bobbin: 110 mm                                                      Success  Yarn-end                                           Edge 2c1                                                                              Edge 2c2  rate     Lgth                                               (mm)    (mm)      (%)      (cm)   Cause of failure                            ______________________________________                                        1       2         100      70                                                 1       3         100      73                                                 2       2         100      110                                                2       3         100      115                                                2       4         95       152    Tension reduction                           3       3         90       500    Tension reduction                           3       4         10       750    Tension reduction                           3       5         0        --     Tension reduction                           ______________________________________                                    

In the above combinations, if the edge 71c1 is 3 mm and the edge 71c2 islarger than 3 mm, the movement of yarn from the yarn-catching part tothe outer periphery is delayed, whereby a yarn-end length of longer than500 cm is wound on other than bunch-winding part. Also the bottomdiameter of the yarn-grip part becomes too small, whereby the yarntension is reduced to lower the success rate of yarn-switching operationto a value less than 90%.

Accordingly, a radius of curvature of the edge 71c1 is preferably lessthan 2 mm, and that of the edge 71c2 in a range between 2 and 4 mm.

FIG. 38 is a schematic sectional view of a third embodiment of a bobbinaccording to the present invention and FIG. 39 is that of a fourthembodiment, wherein a bobbin 70 consists of a cylindrical body 71 formedby laminated paper and a surface paper 72 adhered to the outer peripheryof the cylindrical body 71, and a protective member 73 covering at leastone end surface and part of outer periphery in the vicinity thereof.

While the protective member 74 is preferably formed by adhering a thinpaper having a thickness of less than 0.1 mm, it is also possible topress-fit a cup-shaped member into the cylindrical body 71, which memberis produced by an injection-molding of polymer material such as ABSresin or vinyl chloride resin and has a thickness in a range between 0.5mm and 2 mm, preferably 1 mm.

As shown in FIG. 38, the above protective member 73 is attached bymeans, for example, of adhesive so that a step is formed between theouter peripheries of bobbin 70 and protective member 73 or no step isformed on the outer periphery of bobbin 70.

When the yarn is wound on the bobbin 70, the caught yarn is brought intocontact with the slanted surface 71b or vertical surface 71a andimmediately lifted up by a frictional force onto the outer periphery toform a bunch-winding 90b thereon, whereby it is possible not only toreduce a length of yarn end 90a extending out of the bunch-winding partto abut 115 cm or less, but also to form the bunch-winding 90b at aposition apart by 5 mm to 10 mm from the bobbin end.

While the length of yarn end 90a is one measured when the yarn isextended in a straight state, the actual yarn end 90a is in a rangebetween 20 cm and 30 cm because it is in a crimped state when broken.

Also the yarn end 90a is fixed by the bunch-winding 90b not to beunwound even though it is drawn.

As a result, as shown in FIG. 40, a package 90 provided with abunch-winding 90b for securing a yarn end 90a, a tail-winding 90c and ayarn layer portion 90d, which are sequentially formed on the outerperiphery of bobbin 70 from one end thereof.

If a yarn is wound on a bobbin shown in FIG. 37, a package 90 shown inFIG. 41 is obtainable, while, if wound on a bobbin shown in FIG. 38, apackage 90 shown in FIG. 42 is obtainable.

EFFECT OF THE INVENTION

Since the inventive method for winding a yarn comprises the steps ofengaging a running yarn with a yarn-catching part formed by a boundarypart between ends of the adjacent bobbins fixedly carried on a spindleor a boundary part between one end of a bobbin and a side wall of astepped portion of the spindle for positioning the bobbin, moving theyarn from the yarn-catching part to a bunch-winding position of therespective bobbin immediately after the yarn is caught by theyarn-catching part, forming a bunch-winding at the bunch-windingposition, forming a predetermined tail-winding, and initiating thenormal yarn winding operation while reciprocating the yarn by a traverseguide, it is possible to use a tube made of synthetic resin or aluminumalloy having no yarn-catching groove as a bobbin for winding a yarn.This enables the bobbin to be reused. Also it is possible to obtain apackage in which a yarn length in the yarn-catching part between theyarn-catching position and the bunch-winding beginning position can bereduced,

whereby the entanglement of yarn extending from the bunch-winding andhanging down during the doffing operation with another full bobbin canbe obtained.

Since the bobbin 70 has no yarn-catching groove, it is possible toeasily carry out the removal of bunch-winding in a shorter time.

Since a winder according to the present invention comprises an upperyarn path restricting guide upstream of a contact roller, for guiding arunning yarn to a bunch-winding position, and a yarn-winding guide forengaging the yarn running while being guided by the upper yarn pathrestricting guide with a yarn-catching part of an empty bobbin fixedlycarried on a spindle, positioned in a concave space formed between thecontact roller and the empty bobbin fixedly carried on the spindle, itis possible to assuredly wind the yarn in the yarn-catching part, afterwhich the yarn thus caught by the yarn-catching part immediately movesto a bunch-winding position and is wound thereon. Thereby thebunch-winding is assuredly formed at a predetermined position and a yarnlength from the yarn-engaging position in the yarn-catching part to thebunch-winding beginning position can be reduced.

Also, since it is possible to reduce a rotational angle (θ) of thespindle between the catching of yarn by the yarn-catching part and thebeginning of winding, the tension reduction can be minimizedaccordingly, whereby the success rate of the yarn-switching operation isimproved.

That is, FIG. 48 illustrates a yarn tension variation according to theinventive yarn-switching method obtained from a yarn tension measurementsimilar to FIG. 49. As apparent from a graph T in FIG. 48, in the yarntension in the inventive yarn-switching method, a degree of reduction ofyarn tension at a yarn-switching instant t3 is significantly less thanthat resulting from the conventional method shown in FIG. 49. Thereby,according to the inventive yarn-switching method, no yarn is wound dueto slack around a take-up roller disposed upstream of the winding part,whereby the yarn-switching operation can be assuredly conducted.

If the inventive winder comprises an upper yarn path restricting guideupstream of a contact roller, for guiding a running yarn to abunch-winding position, and a yarn-winding guide for engaging the yarnrunning while being guided by the upper yarn path restricting guide witha yarn-catching part of an empty bobbin fixedly carried on a spindle,positioned in a concave space formed between the contact roller and theempty bobbin; the yarn-catching part being formed by a boundary partbetween ends of the adjacent bobbins fixedly carried on a spindle or aboundary part between one end of a bobbin and a side wall of a steppedportion of the spindle for positioning the bobbin, the yarn can be morereliably caught by the yarn-catching part and immediately moved to thebunch-winding position, whereby reliable bunch-winding is formed at apredetermined position and a yarn length from the yarn-engaging positionin the yarn-catching part to the bunch-winding beginning position can bereduced.

Since a yarn-winding bobbin according to the present invention may haveat least one end surface of a cylindrical hollow body, formed by aninner side wall generally perpendicular to a lengthwise axis of thecylindrical body and an outer slanted wall extending outward from theouter edge of the cylindrical body to the side wall and connected withthe outer periphery of the cylindrical body via a circularcross-sectional wall having a radius of curvature of not more than 2 mm,the yarn is assuredly guided to the yarn catching part by theintroduction part formed with a slanted surface and caught thereby.Thereafter, the yarn is immediately moved to the outer periphery whileengaging with the slanted surface, and reliably forms the bunch-winding.

As a result, it is possible to reduce the yarn end length extending fromthe bunch-winding and form the bunch-winding in the vicinity of bobbinend, whereby a bobbin length can be shortened.

Similar effects are obtainable if the bobbin has a structure whereineach of the opposite ends of a cylindrical body is formed by a side wallgenerally perpendicular to a lengthwise axis of the cylindrical body andwherein one of the side walls is connected with the outer edge of thecylindrical body via a circular cross-sectional wall having a radius ofcurvature of not more than 2 mm and the other of the side walls isconnected with the outer edge of the cylindrical body via a circularcross-sectional wall having a radius of curvature larger than that ofthe former circular cross-sectional wall. Also, if the bobbin is formedof a cylindrical body of laminated paper wherein a side wall of therespective end or one end of the cylindrical body and the outerperiphery of the cylindrical body in the vicinity thereof are coveredwith a protective member, the deformation can be avoided even if it isrepeatedly used. For example, the life of the inventive bobbin in therepeated use is prolonged about three times relative to the conventionalbobbin.

On the other hand, a yarn package according to the present invention isformed on a bobbin having at least one end surface of a cylindricalhollow body, formed by an inner side wall generally perpendicular to alengthwise axis of the cylindrical body and an outer slanted wallextending outward from the side wall and connected with the outerperiphery of the cylindrical body via a circular cross-sectional wallhaving a radius of curvature of not more than 2 mm, while sequentiallyforming from said end of the cylindrical body a bunch-winding foranchoring a yarn end, a tail-winding and substantial yarn-layers.Thereby a yarn end becomes shorter and is anchored by the bunch-windingnot to unwind, whereby the doffing operation and the transportation ofpackage can be easily carried out. Also, since the V-shaped groove isnot provided for catching a yarn as in the conventional bobbin, theremoval of bunch-winding and tail-winding for the purpose of easing thepost process can be easily carried out.

Similar effects are obtainable by the yarn package, formed on a bobbinhaving a structure wherein each of the opposite ends of a cylindricalbody is formed by a side wall generally perpendicular to a lengthwiseaxis of the cylindrical body and wherein one of the side walls isconnected with the outer edge of the cylindrical body via a circularcross-sectional wall having a radius of curvature of not more than 2 mmand the other of the side walls is connected with the outer edge of thecylindrical body via a circular cross-sectional wall having a radius ofcurvature larger than that of the former circular cross-sectional wall,while sequentially forming from the end of the cylindrical body abunch-winding for anchoring a yarn end, a tail-winding and substantialyarn-layers.

In addition, the yarn package may be formed on a bobbin formed of acylindrical body of laminated paper wherein a side wall of therespective end or one end of the cylindrical body and the outerperiphery of the cylindrical body in the vicinity thereof are coveredwith a protective member, while sequentially forming from the end of thecylindrical body a bunch-winding for anchoring a yarn end, atail-winding and substantial yarn-layers, so that the deformation isavoided even if a shock is applied to the bobbin during the doffing andtransportation of the package.

We claim:
 1. A method for winding yarn, comprising the steps of:mountingat least two adjacent bobbins on a spindle to be fixedly carried on thespindle and in contact with a contact roller, and forming ayarn-catching part between adjacent ends of the at least two fixedlycarried bobbins or between one end of one of the at least two adjacentbobbins and a stepped side wall portion of the spindle for positioningthe bobbins; providing a yarn winding guide facing a wedge shaped spaceformed between the contact roller and one of the bobbins, the wedgeshaped space, in a cross section transverse to the axis of the spindle,converging toward a nip point between the contact roller and thebobbins; relatively moving the yarn-winding guide and the nip pointtoward each other, causing a running yarn to be engaged by saidyarn-catching part, thereby causing the yarn to be instantly freed fromthe yarn-winding guide and to be wound on an empty one of the bobbinsafter a fraction of one complete rotation of the empty bobbin andallowing the yarn to be instantly moved to a bunch-winding position ofthe respective at least two bobbins; forming a bunch-winding at thebunch-winding position, and then forming a tail-winding; and initiatinga normal yarn winding operation while reciprocating the yarn by atraverse guide.
 2. A yarn winder comprising:a spindle on which bobbinsare fixedly carried, the spindle having an axis; a contact rollerpositioned for contact with the bobbins on the spindle; a yarn-catchingpart formed at an end of each of the bobbins to engage a running yarn;an upper yarn path restricting guide located upstream from the contactroller for guiding the running yarn to a bunch winding position of acorresponding bobbin; a yarn-winding guide arranged to face a wedgeshaped space formed between the contact roller and one of the bobbins,the wedge shaped space, in a cross section transverse to the axis of thespindle, converging toward a nip point between the contact roller andthe bobbins; and means for effecting relative movement of theyarn-winding guide and the nip point toward each other while the yarn isguided by the upper yarn path restricting guide, thereby causing therunning yarn to be engaged by said yarn-catching part, to be instantlyfreed from the yarn guide and to be wound on the bobbin after a fractionof one complete rotation of the one bobbin, allowing the yarn to beinstantly moved to a bunch-winding position of the respective bobbin. 3.A yarn winder comprising:a spindle on which at least two adjacentbobbins are fixedly carried, the spindle having an axis; a contactroller positioned for contact with the at least two bobbins on thespindle; a yarn-catching part formed between ends of the adjacentfixedly carried bobbins or between one end of one of the at least twobobbins and a stepped side wall portion of the spindle for positioningthe bobbins; an upper yarn path restricting guide located upstream fromthe contact roller for guiding a running yarn to a bunch windingposition of a corresponding bobbin; a yarn-winding guide arranged toface a wedge shaped space formed between the contact roller and thebobbins, the wedge shaped space, in a cross section transverse to theaxis of the spindle, converging toward a nip point between the contactroller and the bobbins; and means for effecting relative movement of theyarn-winding guide and the nip point toward each other while the yarn isguided by the upper yarn path restricting guide, thereby causing therunning yarn to be engaged by said yarn-catching part, to be instantlyfreed from the yarn-winding guide and to be wound on the bobbin after afraction of one complete rotation of the bobbin, allowing the yarn to beinstantly moved to a bunch-winding position of the respective bobbin. 4.A yarn winder according to claim 3, wherein each of said bobbins isformed as a cylindrical hollow body formed at least at one end with aradial inner end surface extending substantially transverse to the axisof the spindle and a radial outer end surface extending from said innerend surface, the outer end surface being inclined, with respect to theinner end surface, toward an outer cylindrical surface of thecylindrical hollow body, and joining with a rounded edge between theinclined outer end surface and the outer cylindrical surface of thecylindrical hollow body, the rounded edge having a radius of curvatureof not more than 2 mm, the rounded edge of one of the bobbinscooperating with a rounded edge of an adjacent bobbin to form saidyarn-catching part therebetween.
 5. A yarn winder according to claim 3,wherein each of said bobbins is formed as a cylindrical hollow bodyhaving first and second axially spaced end surfaces, each of said endsurfaces being formed, at its outer periphery connecting with an outercylindrical surface of the cylindrical hollow body, with a rounded edgeof a radius of the curvature which is larger than a radius of thecurvature of the edge at the second end surface.